Automatic telephone-exchange system



J. W. LATTIG AND C. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT-1 I, 1909.

1,355,983. Patented Oct. 19, 1920.

6 SHEE1S-SHhETI.

J. W. LATTIG AND C. L.'GO0DRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT-11,1909.

Patented Oct. 19, 1920.

8 SHEETS-SHtET 2.

- Quorum:

J. W. LATTIG ANDC. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT- I I, 1909. 1,355,983.

Patented Oct. 19, 1920.

6 SHEETS-SHEET 3.

J. W. LATTIG AND C L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

- APPLICATION FILED SEPT- 1 1909. 1,355,983. Patented Oct. 19, 1920.

6 SHE1SSHEET 4.

1/93 h 1 mom J. W. LATTIG AND C. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. II. 1909.

1,355,983. Patented Oct. 19,1920.

6 SHEETS-SHEET 5.

wmmm I I I fldfi w W M J W LATTIG AND C L GOODRUM AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT-11,1909- 1,355,983, Patented Oct. 19, 1920.

6 SHEETS-SHEET 6.

anvevnroul jligi m UNITED STATES liTENT OFFICE.

JAcoB wqLA'rrm, F GLENSIDE, PENNSYLVANIA, AND CHARLES L. GooDnUM, on URBANA, OHIO, ASSIGNORS, BY MESNE ASSIGNMENTS, 1'0 WESTERN ELECTRIQ COMPANY, INCORPORATED, A CORPORATION 01' NEW YORK.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

To all whom it may concern:

Be it known that we, J ACOB W. LATTIG, a citizen of the United States, residing at Glenside, Montgomery county, Pennsyl- 5 Vania, and CHARLES L. GoonRUM, a citizen of the United States, residing at Urban-a, C-hampaign county, Ohio, have invented certain new and useful Improvements in Automatic Telephone-Exchange Systems, of which the following is a specification.

Our system relates to automatic telephone exchange systems and more particularly to that class of automatic exchanges in which a two-movement, or what has been termed the up-and-around, switch is used for each subscribers line for making connections, the subject matter of the present application except as to certain details being disclosed in our application Ser. No. 222,657, filed August 29th, 1904.

It was common at the date of our original application to employ automatic switches in which wipers. on a vertical shaft were arranged to contact with terminals in banks to which various subscribers lines and operating circuits were connected, these switches being capable of a vertical movement to carry the wipers to difi'erent rows of contacts and a rotary movement to carry the wipers to different contacts in the horizontal rows. Systems employing suchswitches, however, had not been made commercially practicable in which central energy was em.

ployed at the exchange both for operating the switches and for talking purposes and one of the primary objects of our invention was to devise circuits and apparatus by which central energy could be employed with such a system and in connection with party lines, measured service, substations, repeating trunks, etc., these various features having been set out in the original application.

The particular feature to which the present application relates is the arrangement of circuits and apparatus for operating the switches at foreign exchanges or which are located at a distance and in which trunks are used for making connections from a switch at one exchange to another switch, or to substations in which the impulses from the subscribers station are repeated through the said trunks to the controlling mechanism of the switches at the other or sub ex- Specification of Letters Patent.

Patented Oct. 19, 1920.

Application filed September 11, 1909. Serial No. 517,312.

change, both in making the connection and dlsconnectlon of the said switches, the circults and arrangements being such that they would be adapted to use either with or without the central energy.

A further object of the invention is to provide means by which either the called or the calling subscriber may disconnect the connected lines under different conditions, either at the close of the conversation or in case the called subscriber does not answer.

Further objects of the invention will appear from the description of the apparatus which follows and from the claims attached thereto.

In the drawings, Figure 1 is a diagrammatlc view showing a subscribers station and the connections from said station to the first selector switch which is individual to that line, also illustrating multiple connections for said subscribers line to other switches, the switch here shown being for convenience hereafter termed the first selector switch. Fig. 2 is a diagrammatic view of the apparatus and circuits of the repeating trunks containing relays which repeat impulses coming from the subscribers station through a first selector switch, which trunks lead to other switches which are generally arranged at remote distances, such as in other exchanges or sub-stations. Fig. 3 is a diagrammatic view showing the circuits and apparatus for the second selector switches which may be connected directly to the individual or first selector switches or by means of the trunks in Fig. 2, in which case they are connected through the repeating relays. Fig. 4 is a diagrammatic view showing the arrangement of the apparatus and circuits for the connector switches which are generally arranged in succession to the second selector switches, but which might be connected thereto by means of the repeating trunks, as shown in Fig. 2. Fig. 5 is a diagrammatic View of a subscribers station and its first selector with the bank terminals of the connector, shown in Fig. 4, through which connection is made to said subscribers station when it is a called station. Fig. 6 is adiagrammatic view showing the repeating relays and trunks permanently tied to a second selector switch. such as shown in Fig. 3, in which case the bank contacts, at the left of Fig. 3, are dispensed and the bank contacts to the left of F1 2 take the place of said contacts, all impufses passing to this selector switch or successive selector; or connector switches being repeated through the a aratus, therein shown, and also shown in i 2. In further explanation of tie arran ement of the drawings it will .be noted that igs. 3, 4 and 5 are so arranged that the right edge of one sheet is adapted to join on to the left edge of the succeeding sheet, which would ive the ordinary connection, such as used in a single exchange, while Ifig, 2 shows the arrangement of the repeating relays and trunks to be used in case connection is to be 7 made to a foreign exchange or a substation, for the purpose of repeating the imulses to the switches-which are located at a distance, and Fig. 6 shows substantially the same arrangement. with the connection actually made, being, in effect, a consolidation of Fi s.2 and 3.

brief outline of the system is as follows: Our talking circuits are metallic; that Y is, each circuit is composed of two line wires. Each' line comes into the exchange and is there connected to its first selector and also is connected to multiple contacts in several banks of the connector switches. In addition to the two-line wires an additional circuit or ground return is employed for sending impulses by means of which the switches are operated. 1

Each selector switch is a self-contained unit, individual to its line and preferably contains a multiple contact for each of the second selectors in case the exchange has over a thousand lines, or for each connector in case the exchange has less than a thousand .lines. Each second selector is also a selfcontained unit connected in multiple to the banks of the first selectors and each contains a multiple contact in its banks for each of the connector switches. Each connector is a complete switch unit connected in multiple to the banks of the various second selectors in an exchange of over one thousand, or to multiple terminals in the first selector banks in case the exchange is under a thousand, and

each connector also contains in its banks contacts for the subscribers lines falling stations or remote groups.

in a similar manner to connect with the terminal contacts of an idle connector in the group corresponding to thehundreds digit of the number wanted. The operatic of this switch cuts off the operating me amnism of the second selector after which, by

similar impulses from the calling station,

the connector switch is automatically o perated to select a multiple terminal of the particular subscribers line wanted. As the connection progresses step. by step through the various switches, the metallic talking circuit of the subscriber calling is correspondingly extended through the first and second selector switches and the connector switch. Means are employed, including condensers, by which the main battery is bridged across the circuit from the end toward the called subscriber but, until the latter answers no battery flows to the calling end. The signaling or impulses for operating the switches is accomplished over one or the other of the line wires and the ground connection.

The connection having been completed and the called lines not being found busy, the calling subscriber signals the called subscriber by pressing a signaling button at his station which operates a ringing relay in the connector circuit and thus applies a ringin current on the wanted line. When the ca led subscriber answers, apparatus is automatically operated at the exchange by which battery is connected back to the calling end of the talking circuit. The .switches .are released by the subscribers hanging up their receivers, a release magnet connected to each of the switches being operated automatically to restore the switches to their normal position. w

The description thus far relates to the cir.

cuits and the manner of making connections when the connections are to be made all within one exchange. Where, connections are to be made to sub-stations, or groups of subscribers at a distance, repeating relays are placedin the line by which the impulses from the calling station are repeated to the switches which are to be operated at the sub- In case of a complete sub or branch'exchange with first and second selectors and connector switches, these repeating relays would be placed in trunks leading from the first selectors or the switches individual to the lines to the second selectors at another exchange. In other cases these repeating relays are placed in trunks leading from the individual or first selector to the connector switches, then the said selector switches, as well as the connector switches, would be successively operated by means of the im ulses from the subscribers station's who are repeated successively to the selector switches and then to the connector switches.

Fig. 1 shows a pair of line wires li 12 constituting a subscribers line circuit and extending from the first selector or in dividual line switch, S, to the subscribers station, A. Each subscribers station is provided with the usual transmitter T, receiver R, induction coil 2' switch hook H, ringer Q- and condenser In addition to these usual instruments any suitable form of impulse transmitter is provided to successively ground the sides of the line for the purpose of sending impulses over the line, in a well known manner, this particular apparatus forming no part of our invention as such apparatus was in common use in what was generally known as the Strowger system. As before stated, our system is adapted to be used with the two-movement switches, which have a vertical and rotary movement, such switches being also common to the Strowger system and for this reason the diiferent wires of the line circuit are usually termed vertical line and rotary line. These impulses are given by grounding the vertical side of the line a desired number of times, which is followed by grounding the rotary side of the line with a single impulse. In-

asmuch as this is a decimal system the im-' pulses necessary to produce a given movement of any switch will not exceed ten.

In the diagrams we have used the usual Strowger diagram of impulse transmitter in which an arm, a, is adapted to' move into engagement with a contact, a or a and thus ground either side oi the hue. It should be explained that the circuit breaker,

a", must be grounded when the impulses are i being sent and in the Strowger apparatus means are provided for closing the circuit from ground to the lever a by the movement of the calling dial and also for opening the branch including the talking instruments, otherwise both sides of the line would be tied together and both sides of the line would be grounded.

Receiver R is shown in a local circuit 21 terminating in one winding of the induction coil, 2', this being, in effect, the same as cutting off the receiver by a condenser so that battery current will not fiow through it and its resistance is removed from the line. The

transmitter circuit for a common battery or central energy system maybe traced as follows: from vertical line wire 11, by branch 3, wire 25, wire 26, spring a spring a", wire 24, springs a and a, one winding of induction coil, 71, wire 23, transmitter T, and thence by wire 22, springs a and a", and wire 21, to the rotary side 12 of line through branch 4. The ringer, Q, is in a ground tap from branch, 4, on the rotary side of the line with an interposed condenser C. The spring, a, is grounded at G throu h resistance, r, for the purposes present y disclosed.

It is to be understood that no substantial change is required in the subscribers instrument to convert this system into a local battery system, the apparatus remains the same the only change being in the receiver and transmitter WlI'lIlg and special battery at each sub-station.

The metallic talking circuit or subscribers linewires, 11 and 12, pass to the first selector Similarly and synchronously the other arms move into engagement w1th their corre-' sponding contacts during the operation of the apparatus, as hereinafter described, being normally in engagement with the contact, f", in each case.

The vertical wire, 11, is normally connected through arm, 7, and wire, 30, to the vertical relay, D, thence by wire 31, through cut-ofi' springs 70 I0 and 72 and wire 32 to the main grounded battery, B, (shown in Fig. 3) 32 being the battery wire. The rotary side of the line or wire 12 is normally connected through arm, F, by wire, 34, to the rotary relay, E, thence by wire 33, springs 72 and 70 to{ wire 32 and thus to battery.

The main switch consists of a vertical spindle, c, which carries wipers or contact springs, 12 and o ,which are adapted to successively engage and make connections with the bank contacts, m and m (Fig. 2). These bank contacts are arranged in horizontal rows, preferably of ten each. The banks of rows are curved in semi-circular form with a center in the axis of the vertical' spindle, o. In order to bring the wipers into connection with any particular contacts, m and m therefore the vertical spindle, o, is first stepped up or raised vertically until each wiper is opposite the desired row and then is caused to rotate step by step until the wipers make connection with the desired contacts or terminals in the row. The first movement of the'spindle is called the vertical and the second the rotary movement.

It will he noticed that the wipers, o and o", are normally connected to the contacts, 7"", of the side switch arms, f and P, so that, in their normal condition with these side switch arms in connection with their contacts f", the line wires, 11 and 12, are disconnected from the wipers 1'0 The vertical relay, D, controls, through its armature, a contact spring, (I, which conmeets with a grounded contact, 9, the spring, d, is connected by wire 37, through the springs, p and p and wire 38, to the vertical inotor magnet D thence by wire 38, to the main battery wire 32. This vertical motor-magnet, D is the magnet which actually steps up the shaft, '0, or produces the vertical movement thereof.

The relay E, through its armature, controls the spring, 0, which is adapted to close on the same grounded contact, 9, the spring, 6, being connected by wire 39 to what 1s called the private magnet P and thence to main battery wire 32. From the wire 39 a branch 40 extends to the second contact f of the side switch arm, f When the side arm, F, is on this contact the circuit would be continued through the back release relay J to the private contact, 42 by wire 52.

Normally, however, this magnet is cut off.

The relay, J, through its armature, 7', controls the spring contacts, j and 7' which, whenthe armature is attracted, closea circuit from ground by way of wire 41 to the release magnet, I, said magnet receiving current over the wire, 41, which is connected to the main battery wire 32.

It will be observed that the armature, p, of the private magnet, P, controls the springs, 2 p and p, the latter two of which also control a gr amd connection for the magnet, I, by waygf wires 37, 37 and spring (I. It is ne","ss ry, however, that the magnets of bot 6 vertical relay and the rotary rela be energized 1n order to close this cgcuit as the private ma 'net, P, is controlle b the rotary rela This means that bot the vertical an rotary relays, D and E, must be simultaneously energized in order to close the release circuit. The private magnet, P, controls the side switch, F, in the usual manner. When the release magnet, I, permits the parts to return to normal position, all the switch arms of side switch, F, are returned to normal position, as shown in Fig. 1. At each. retraction of the armature, p, of the private magnet, P, these switch arms are all advanced one step by means of an escapement not shown controlled by the said armature, p.

As before stated, each line has a first selector, such as shown in Fig. 1, with the individual selective wipers, '0 and these wipers are adapted to connect as the switch isoperated with multiple contacts, m These multiple contacts, m represent the terminals of the wires 13 and 14 leading to the various second selector switches. These wires, 13 and 14:, re resent trunk lines and, as the trunks are on y used at any one time by a limited number of subscribers, they are less in number than the lines of thefirst selectors, say, ten per cent. thereof,

which are further extended trunks.

The same may be said of the connectlolil's e multiple contacts, at, in the first selectors represent terminals of lines leading to second selectors, and the multiple contacts 1n the second selector represent multiple terminals leading to the connectors, the multiple contacts in the connectors, however, are connected directly to the subscribers lines and in multiple to their first selectors.

In the drawings Fig. 4 shows a connector switch whose multiple contacts, m see Fig. 5, represent terminals of different subscribers lines or stations. The same connector would contain multiple contacts, m, for example, for the line No. 1920 (see Fig. 5) and likewise would contain multiple contacts, such as m, corresponding to the line 1112 or station A (see Fig. '1) provided the said station were in the same hundreds division for which that connector switch is appropriated. The connector switches are arranged in groups and since the decimal system is used in the present case for convenience each group has multiple contacts or terminals of subscribers lines or stations whose numbers all have the same hundreds digit, thus there will be one group of connector switches for subscribers from one to one hundred, another groupfor those from 101 to 200, another for from 201 to 300 and so on. In the same way the second selectors are divided into groups according -to the thousands and each second selector has multiple terminals for all the connectors within its thousand. Thus there will be multiples in one group of second selectorsfor all the connectors between one and one thousand; that is 100, 200, 300 and so on to 900 which selects up to 999. As already stated, if the exchange is limited to one thousand or less,

the second selectors can be dispensed with. In each first selector then every horizontal row of contacts would represent a separate hundred and each contact in that row a separate connector switch in that one hundred group, all the connectors in one grouprepresented by 13 and 14 and are tied to side switch arms, 7 and f". E is the rotary relay and D the vertical relay of the second selector. The vertical relay, D is in a branch line 45 which leads from contact f of side switch arm, f, to the relay E and thence to the battery wire 32. The rotary relay, E is in a branch 46 connected to'contact f of side switcharm, f", to battery wire 32. Inasmuch as all the switch arms are normally on their contact f", the vertical relay, D is normally connected to the vertical side of the'line and the rotary rela E is normally connected to the rotary si e of the line 14, whereas the other terminals of both of these relays are connected to' grounded battery B. he armature of the vertical relay, D controls a spring, (1 and a mechanically connected but electrically separated spring, d which latter closes on the ground contact, 9 when the armature is attracted. The armature of relay, E controls a spring, 6 and the mechanically connected but electrically separated sprmg, e", which latter closes on the ground on contact, 9 when the armature 1s attracted. The two springs, 01 and e have curved ends adapted to come together and make electrical'contact, when both armatures are slmultaneously attracted, at the point, m, but not when either .armature is attracted separately. When the vertical relay, D is energized it closes a circuit-through the vertical magnet, D from ground at contact, g, spring, d contacts (i -11 on the private magnet, P vertical magnet, D to battery wire 32. When the rotary relay is energized it closes a circuit through the private magnet, P grounded contact 9, spring 6 private magnet P thence to battery wire 32,;thus energizing the private magnet P to operate the side switch F The release relay, J is in a circuit which extends from switch arm, I" to wipers, '0, of the second selector switch. The release magnet, P, for the second selector is in a circuit from battery wire 32, wire 50, magnet I, wire 51, spring 6 sprin (Z wire 47, wire 49, contact m wipers '0 Fig. 1) wire 52, release relay 3, of the first selector, switch arm 7, contact f to ground G, this circuit being normally open at the contacts, at, and at side switch arm, f Fig. 4 shows the connector switch and apparatus and wires 15 and 16 which constitute the talking circuit are connected tothe terminals, m m of the second selector wire 56, spring 57, contact spring 58,'wirev switch (Fig. 2) which are adapted to make separated conductively but jointed inductively, the extension of the lines beyond the condensers being marked 15 and 16*. D is the vertical relay and E" is the rotary relay. The vertical and rotary relays are in a circuit from line 15, by wire 55, relay D,

61, spring 62, contact 63, wire 60 to rotary relay E and thence to line wire 16. The relays D and E are thus bridged across the line wires 15 and 16 through contacts 62 and These WIIGS.

63 of the ringing relay, W, and 57-53 of relay, V, hereinafter described. Each is also supplied with a battery supply. connection through spring 59 which is connected to battery wire 32.

The vertical relay,'D*, through its armawhich are brid ed across the extended lines,

15 and 16", wit battery interposed through c the following circuit: from wire 15", at 200, by wire 201 to relay V, wire 202 to ground, by ground to grounded side of battery B,

D and E, are bridged across the lines 15 and 16. I also proyide relays V and V battery wire 32, wire 203, relay V wire 204,

to line wire 16* at 205. The extended lines 15 and 16, are connected through circuit breakers operated by the ringing relay, W, to the slde switch arms, f, f, and when out through by the connector switch to the called subscriber, the relays V and V will be bridged across the called subscribers line and separated from the calling subscribers line by the condensers, C, so that these relays would be siiiiultaneously energized by the closing of this end of the line when the called subscriber removes his receiver. Relay V however, through its arma- 1 ture, controls normally closed contacts while relay, V controls normally open contacts and by reason of the fact that the first movement of the armature in one case will open the closed contacts while there is an interval of time in movement of the armature, required to close the open contacts, that relay which is operating on the normally. closed contacts will break the contacts beforethe other relay will close the normally open contacts although simultaneousy energized and these relays are so arranged as to perform this function; that is to say, when they are simultaneously energizing the one which is operating the closed contacts to open them will break the connection before the one which is operating the open contacts will close the connection and this is true whether the relays are being energized or denergized, the closed contacts will always be opened before the open contacts are closed, when the "relays are simultaneously energized or deenergized. The relay, when energized,closes a circuit from line wire 15, throu h wire 76, gpring 77, contact 78, and wire 79 to relay and thence to ground; also a circuit from battery wire 32, bywire 71, relay Y, wire 72, spring 73, contact 74, wire 75, to the line wire 16, the battery B being grounded-the relays, X and Y, would thus be bridged across the line wires 15 and veration of the relay V .16 with battery interposed. Battery would thus be supplied to each end of the line separated by the condenser, 0 upon the op The rotary and vertical relays, D and E, being bridged across the line through contacts 57- and 58, operated by the relay V, would be disconnected prior to the time that the relays, X and -Y, are connected to this line, for the reasons before stated; that is, the relay, V," operating to break the contact would break the circuits for the relays, D and E, be-' fore the circuits for the relays, X and Y, would be closed, althougR the relays are operated simultaneously. elay X is adapted,

when energized, to break the normal lg v closed contacts, 00 and on, while relay, when energized, is adapted to close the contacts, 3 and 1 The making and breaking of these contacts has reference to the release circuit which will be hereinafter more fully described.

Attention is called to the fact, at this point, that the relays, X and Y, are similar normally closed contacts and the closing of the normally open contacts by simultaneously operated rela s is essential to the successful operation 0 these circuits, as will be more fully hereinafter described.

' The armatures of the respective relays, D

and E, are provided with contacts, 00, adaptf-e d' to make electrical connection when bothrelays are operated simultaneously to close the circuit through the release magnet, J,

- in,,' the manner hereinafter more fully -de e will now assume a call to originate at 'nd describe the operation of extending hisjfcall to'the station, A, which we will I assume is No. 1920: After taking down the receiver the subscriber operates his im ulse -.,-transmitter to ground the vertical si e of the line as many times as there are units in the thousands digit. In this case, assuming the number to be 1920, there would be one impulse only, but the impulse transmitter being so arranged that upon the conclusion of its operation it sends one impulse over the opposite or rotar side of theline, we will have one impu se transmitted from ground over vertical side of line followed by one impulse from ground over the rotary side of the .line. The first impulse over the vertical side of the line energizes the verti- This elecal relay, D, over the following circuit:

From the grounded contact a, :spring a, line 3, line '11, side switch arm )9, contact. f",

line. 30, relay D, contacts 7t, k and k, to 3 wire 37, spring p, contact p wire 38, vertical motor magnet D wire 38, wire3 2 to battery and ground. The energizing of the motor magnet, D steps up the vertical spindle, v, as many steps as there-are impulses,

in'this case there being but one impulse the vertical spindle, o, Wlll bestepped up one step or to the first thousand or to the bank representing selectors for the first thousand. Asthis impulse is followed in the transmitter by an impulse over the rotary side of the line, the relay, E, will be energized over the following circuit: from grounded contact a spring a, line 4, line 12, side switch 7, wire 34, relay E, wire 33, contact contact k battery wire 32, battery and ground. The energizing of the relay, E, will energize the private magnet, P, over the following circuit: from gigounded contact 9, spring e, wire-'39, relay wire 32, to battery and ground. This produces an impulse in the private magnet P which, through the mechanical mechanism of the switch, operates the escapement mechanism to cause the side switch F, to move over'to the second position. This brings the switch arm, onto the second contact f which cuts in the rotary motor magnet E line 38, line 32 to battery and ground. This rotary mo tormagnet is so arranged that so long as it is in circuit it is operated by a vibrating current which causes the spindle to be stepped around so longnas'current is sup plied to said magnet.

is continues until the wi ers, o and 0?, stop on an idle contact. his particular arrangement is common in switches of this kind and forms no part of our invention. The result is, however, that when the wipers are started to rotate over a given bank to fi'nd a selector switch in the thousands represented by this bank, it will continue to operate until an idle trunk is found when it will automatically stop and the side switch will be moved .a second step or to the third position. The side switch is preferably .so arranged that in moving from the'first to the second position the verticalrelay D is cutout by the switch arm 1 and in moving from thesec- 0nd to the third position therotary relay. E is cut out by the switch arm f in the usual way. When the'side switch moves to the third osition both sides of the line, 11

and 12, wi l'be connected to wipers, '0 o, by

the switch 'arms, 7" and f, connecting wit the contacts, f.' This would connect station A to the second selector switch. The

. calling subscriber againcgperates' his transm1tter to send nine impulses by closingcon- I circuit for the vertical motor magnet,

tacts a and a-tog'ether nine times, which would be followed by closing the contacts, a and of, to ether once. As before, the nine impulses wi 1 cause the vertical relay, D of second selector to be energized nine times over a circuit from battery wire 32, throu h relay D wire 45, wire 13 back through wire, 11 to the station A and ground and the relay, D is energized successivelynine-times.

and vibrates its armature nine times to circuit of the vertica motor magnet, D

.nine times which steps up the spindle, 0,.

of the secondselector switch ninefrows or to the nine-hundredth row of connector contacts, m The single impulse that follows over the rotary'side .of the line 12 extended to 14 passes through the rotary relay, E

which grounds the spring, 6?, and thereby closes circuit'from battery wire 32, throng private magnet P, the latter openin the contacts, 03 and d, and permitting the side switch, F to move all of its arms, f, f, f and f, to the second position, the arm,

l cutting in the rotary motor magnet,-E t e arms, f and f, cutting out the relays, D and E The arm, 7", connecting the wiper, v", back through the relays J and P to the I battery wire 32. The rotary magnet E being in circuit vibrates andste s around the spindle, o, asbefore, untll t e wipers, 'v and '0, find contacts of connectors that are idle or ungrounded. In this connection weshould call attention to the fact that the instant the spindle, v, in Fig. 1 (first selector) commenced to rise, it released a spring, u, See the left hand side of- Fig. 1) of a switch 7 bridge cut-off relay K, and grounding the wire 35 on the contact n This completed a partial circuit from ground as follows: G, u ,.u, 35, and to all the contacts, on, in'the multiple banks of connectors upon which connection might be made with the rivate bank contacts all being grounded Wlll test busy therefore if anyone else attempts to break in by calling line 1112. Similarly, the instant connection was made between the first selector and the second selector at 12 -472 and the side switch F of the first selector had moved its second step or to the third position, ground on the wire 54 was connected to wire 53, magnet J, andwire 52 to the wiper '0 and thence to all the connected multiple contacts, m of the second selector shown,

wherever they might be distributed, so that no first selector could get in on that second selector while thus in use. v As soon as the second selector finds a connector that is idle, the ground circuit through magnet 15 (Fig. 3) is broken, the

breaking circuitwith contact, u of the "onto 15 16 the arm, cuts off the rotary magnet an thereafter remains open, and

the arm," 7", closes vthe ground of contact,

connector thus selected test busythereafter during the connection.

We have now reached Fig. 4, with a' clean metallic circuit made up of wires 3, 11, 13,

thereby closing the 15, on one side, and 4, 12, 14, 16 on'the other .findthe side switch, F present in this case also, and that it controls the circuits of three flmagnets the vertical magnet D, the rotary magnet andthe ringing relay W.

' The subscriber nowjsends the number 2,

two impulses pass along the wires 15, 13,

11 and 3 and to ground at station A, throughthe connector. circuit as follows: battery B to spring 59, to springs58 and 57, relay D, and wire 55 to wire 15. This vertical relay,

D, then "steps up the spindle, 1:, until its wi ers f0v and v reach their res ective sec- 0nd rows of subscribers contacts. The sin f onto the magnet, ,.and so-to the wiper, g2, whlch being on-tne contact, m, makes- 1t'andits connected multiple contacts of the.

by closing a circuit from the middle contact f, of the lower side switch arm, f back through the release magnet, J and to the battery wire 32. In moving its armature the magnet, P lets the side switch go around one contact, cutting in the rotary magnet, E and connecting the wiper, '0,

through the arm, f,- and contact, f, back to the release magnet as stated. The subscriber now sends the-number 0, which, is ten im ulses over the vertical side of the line. his again works the vertical rela D, as before, which groundsthe spring,- al thereby closing a circuit from ground to spring g and d and thence by wayof wire 64, spring p and 7?, arm f rotary magnet E wire 67 and 32 to battery. The impulse transmitter after sending the ten impulses for the numeral 0 over the vertical side of the line grounds the rotary side, as usual, causing E 'to operate and in turn operate 1 by energizing the following circuit: battery B, wire 32, magnet P springs a and g to ground. This action .has brought wipers 12 and 4) onto the contacts m and m in the bank of the connector shown in Fig. 5 and the side switch has connected lines 15 and 16 to the wipers '0 through side switcli arm I and f and has con- I nected the wiper -vto round through the side switch arm' f". f this line is busy there will be a ground on the contacts, :m, by reason of the switch, U in Fig. 5 belng up against contact, u, or y reason of m being connected in multiple to another connector switch and therefore the instant these contacts, m, are touched P bein energlzed a circuit is completed from the attery, B, through the magnet J Fi 4, whlch attracts its armature and reIeases the stop pawls which retain the -spindle,. 'v, in its rotated and elevated position, restoring the connector to zero. If the s indle, 'v, of the connector had not already n restored to zero the magnets, D and E, would act when the calling subscriber initiates the release. These close their contact s rings, (F -e at. point 90, whereby the. fol owing circuit is completed: battery B, wire 32, J e, (1 to contact m, wiperv, magnet J, arm f, contact f and ground. The magnets, J and J both act, the latter to restore the connector, S, and the former to close the circuit B, 32, 50 I, 51, 49, m, '0 52, J, 53, arm 7, contact' 54 and ground. Whereupon the magnet, I pulls out the pawls that hold the spindle, 'v, of the second selector, S, (Fig. 2), and restores this to zero; while the relay J closes the circuit of the release magnet, I, as follows: batte B, 32, 41', I, 41, j, j, and to groun VVhereupon magnet, I, pulls out-the pawls from the spindle, v, of the first selector (Fig. 1), S, and permits that to go to zero.

I The magnet I, magnet I and magnet J 2 in each case when releasing the pawls from the vertical spindle also pull over the side.

switch, F, F or F to the normal or zero position shown in thefigures. When the spindle, o, of the first selector, S, drops down it takes the ground off the wire 35 by pushin :down the spring, 11, of the switch U. hus all parts are again normal and all switches idle.

Suppose, however, that the line wanted does not test busy. The subscriber after sending in his last number presses his ringing button, which closes. together the springs, (1 and a, to ground the vertical side of line as follows: G, 1', springs a-a,

of line 15 entirely.

a, a, a, a and by wire 25 to the vertical I side of line. This permits current to pass backfrom battery wire 32 in Fig.3 through vertical relay D to the subscribers' station and ground. The spring, d, is again grounded, and circuit completed from ground through springs, pp, and wire 65 to arm contact f", wire 69, the ringing relay and battery by wire 203. This rethe springs thereof, 0 ening the vertical side t also opens the rotary side of line 16 at spring 71 and connects the said spring with the terminal of the ringing generator wire 17 0. Current then passes out through contact m wire 18, wire 20, ringer Q and to ground throu h the condenser at the wanted or called station. After-ringing the calling subscriber, A lets go his calling buttolg, the vertical relay D and ringing relay are deenergized. The armature springs of relay W close the line contacts and a metallic talking circuit is cut through switch hook which t ere'upon closes his metallic talkingcircuit l5" and'16 and thus simultaneously energizes relays V and V bridged across the line with battery interposed. Relay V opens contacts 57, 58 and 59 and thus opens the circuitof the vertical and rotary relays D and E. While relay V closes contacts 73, 74, 77 and 78, thus closing the circuits of relays Xand Y from battery to round and thus simultaneously energizes t e said rela s X and Y. The 0 ening of the contacts y relay V precedes the closing of the contacts by relay V as and for the reasons heretofore described. Re lays X and Y will by the operation of relay V be bridged across the calling end of the line with battery interposed, and this feeds battery to the calling end of the line 15-16,. at the same time these relays being simultaneously energized the normally closed contact w and 42: will be 'opened by relay X followed immediately by the closing of-the normall open contacts 3 y by relay Y; At the cone usion of the conversation when subscriber A hangs up he breaks the metallic circuit and momentarily grounds both sides thereof by closing together the springs a, a and a, and relay X being connected from one side of the line to ground will be thus deenergized and relay Y being connected to the other side and to battery and ground will be energized, the released circuit is thus closed as follows: Battery B, 32, 250, J 70, 70", y, y, 70, m m 7 0, to the contact, m, wiper 1), back release relay J, of the second selector, S to the arm, 7", of

the side switch, contact, f ground and back to battery. Thereupon the release magnet,

J releases the spindle, 'v, of the connector 7 switch, restorin the latter to normal; while the relay, J, c oses the local circuit of the release ma net, I, of the second selector, S and back t rough wire 49 to the release relay J, of the first-selector, which closes the at the called subscribers switch hook. This would cut out the relays X and Y' b the openin of the contacts 73, 74, 77 and 8 by relay which would be immediately followed by the closing of the contact 57, 58 and 59 of relay V, w ich would close the circuit of relays-D and E so that the last mentioned relays would again be bridged across the line'with grounded battery, where upon when the calling subscriber hangs up his receiver the momentary grounding of both sides ofv the line would cause relays D and E to be simultaneously energized, by grounded battery flowing on each side of the line to ground at station A, which would close the release circuit at w. This would operate the release magnets and relays over the circuit just as describedthrough contacts -d at Fig. 4 instead of throu h the line and contact a and m and 3/ an 3 so that in either case the release would be effected by the calling subscriber hanging up whether the called subscriber has hung up his telephone or not.

We will now describe the operation of our trunking apparatus and the method of repeating calls to sub-stations or to remote points.

Referring to F igs. 2 and 6 the trunk l1ne here shown is adapted to form an extension from a given first selector in one exchange to a second selector in the same or a difierent exchange. The ends of the two wires, 18 and 14. in Fig. 2 are supposed to be connected to the wires 13 and-14 in Fig. 3, the release wire 119 of Fig. 2 being the same as release wire 49 of Fig. 3. Fig. 6 shows the connection made, the extension in thls figure being marked 13 and 14. The trunk line is therefore to be considered as interposed between the first and second selectors, the two sides of the line which form the trunk being broken by condensers C The object of cutting the line by the condensers is, for the purpose of supplying a battery to each end of the line for the dlfferent subscribers, so that a subscriber on a short line in conversation will not consume the current to the detriment of a subscriber on a long line.

For the purposeof obviating the effect of the discharge of these condensers the lines are transposed, the purpose and operation thereof hereinafter set forth more fully. In Fig. 2 a double transposition is shown, but this is not necessary as the effect des red may be secured by a 'single transposltion. In Fig. 6 we have shown the trunk repeating apparatus connected with only a single transposition. ofthe line. In this figure the trunking lines 13 and 14" beyond the condensers C taking the place of the lines 13 and '14. in Fig. 3.

In connection with the condenser, means are provided for feeding batteryto the line wires on each side of the condensers for talking purpose and the calling or called subscrlbers are furnished with talking batfrom different sources, so that each' te tal ing instrument would have battery of substantially the same potential, thus" obvlating the drop in the battery potential when the trunk is connected to another exchange or remote point; the direct current from the battery sources being stopped at the condensers while the alternate currents of the subscribers transmitters would pass through the condensers in conversation between subscribers. {Inasmuch as the impulse to operate the switches are impulses of direct current which will not pass through the condensers it is necessary to provide for -passing these impulses around the .con-

densers and for this purpose we provide repeating relays Z and Z which are bridged across the lines 13 and 14 with battery connected thereto, connection being made through contacts adapted to be operated by a relay Z". In Fig. 2 this battery connection is shown from battery B and in Fig. 6 the battery connection is shown to the main battery B. It will be understood that the many batteries shown in the drawings are merely for the sake of clearness, that in operation the main battery B may be used to take the place of these various batteries and a common return or metallic circuit will be made in the well known manner instead of the various ground connections. 7

The repeating relays Z and Z operate somewhat similar to the relays D and E* of the connector switch in Fig. 4:. That is to say, either one of said relays will be energized by the grounding of either side of the line and both will be energized by the grounding of both sides of the line. When either one is separately energized it operates an armature spring to engage a grounded contact and when both are simultaneously energized by grounding both sides of the line, armature springs forming. circuit closers are brought together for olosing'the release circuit as hereinafter described. The armature springs 104 and 105 of relays Z and Z ar connected respectively to the lines 13* and 14 by wires 123 and 121, which pass around the condensers C and therefore impulses which come over the lines 13 and 14 ground the lines 13 and 14 by the operation of said relays and thus repeat the impulses. I

The transmission of impulses to the first selector and the selection of an idle trunk pass direct yinto the second selector being' stopped b the-interposed condensers C.

' The impu ses'which c me over the verticalline 13, however, wil operate the relay Z over the following circuit from batter '10 (B! in Fig. 2 or main battery B in Fig. 6?

-. V through contacts 94, 93 and 92 and wire 91,

- j relay Z, thence by wire 90 to line wire 13 and back to ground at the subscribers station. This energizes relay Z and'causes T15 its armature spring 104 to engage the grounded contact 108, which grounds the trunk .line 135 through wire. 123, spring- 104, contact 108 and ground. The grounding of t nk wire 13" will operate to send an im-" ulse to the second selector switch in the manner heretofore described, thatis to say "the impulse will be repeated from. wire 13 into the trunk 13 and will energize the ver- 1 tical relay D from battery B, wire 32, relay D, wire 45, switch arm f, line wires 13" and to round at 108 over the circuit last describe The single impulse that comes over the rota side 14 of the line will operate .to energize the relay Z over the following circuit, battery (13 or B contacts 94, 93, wires 96, relay Z and wire 95 to line 14 and to round at the subscribers station. The energizing of relay Z grounds its armature spring 105 on contact 108, thus grounding the trunk or extension 14* through wire 121 and this will operate the rotary relay E of the second selector switchin exactly the same way as heretofore described by the grounding of the line 14 at the calling subscribers station when the trunk with the inter sed condensers are not used, in other wor s the impulses will be peate from line 13 to 13 by rela-yZ. After the second selector switch has been properly operated to find a connector switch, the 'connector switch will be operated by impulses from the calling subscribers station re peated by the relay Z and Z in exactly the same way; that is to say these impulses from the calling subscribers station over line 13 would cause the relay Z to ground the wire 123 of the trunk, and as 13*isconnected through the second selector switchto line 15 of the connector switch, the vertical relay of the connector switch would be operated. The impulses coming over wire 14 would 0 crate the relay Z which would ground t e trunk or extension 14 through the second selector switch to wire 16 of the connector switch and thus operate the rotary relay of the connector switch.

' It should be noted that each impulse that 66 comes over the lines '13 and 14 will result line. posed, thatis the trunk or extension 13 is. 1 connected to the condenser in the line wire inthe charging of the 'lines and conse quently the charging of the condensers, connected thereto, witha subsequent discharge. If the lines 13-13? and 14-I14.were connected straight through the condensersC this charging and discharging of the condensers would tend to interfere with or neutralize the impulses transmitted over the To obviate'this the lines are trans- 14 and the trunk or extension 14 is connected to the condenser in line 13. The impulses are repeated from line 13 to trunk or extension 13. around the condenser at which time no im ulses are passing over the line 14, the resufi of this is that the condenser that is being charged from line 13 di'schargesinto trunk or-extension 14 while the impulses around the said condenser are repeated into trunk or extension 13", while the discharge of the condenser which is charged by line 14 is into the trunk or extension 13 the impulses from line 14 being repeated into the trunk or extension 14. Inasmuch as these impulses are transmitted successively over the line wires 1314 the discharge of the condenser is always into the side of the trunk or extension over which at the time no 0 crating impulses are being transmitted, so t at no interference can take place. When the connection is established through the various switches for talking purposes the transposition'of the line produces no effect, as the talking current will flow over the lines and through the condensers the same whether transposed or not.

The connector switch havin been operated to find the wanted subscriber the calling subscriber. would press his ringing button as before to ground the vertical side of the line, which would energize relay Z to ground the. trunk or extension 13, which would operate the ringing relay exactly the same as before described' The called subscriber answers by removing his telephone from the hook and the connection is made by metallic circuit between the calling and called subscriber.

Upon removing his receiver from the 5 hook the called subscriber will cause the operation ofrelay V in Fig. 4 which will connect the battery B'across the line 15-16 the same as before described. Owing, however, to the interposed condensers in the 120 trunk this battery current cannot pass back to the calling subscribers station when the repeating apparatus is used. To obviate this we provide the relays Z and Z, which operate similarly to relays X and Y here- 125 tofore described. These relays Z and Z are connected in normally open circuits.

' from cuit is closed to be connected'to grounded battery. The circuit for relay Z9 may be traced as follows: wire 113, contact 110 and grounded battery B, while the circuit for relay Z is from line 14, wire 114, contact 109 direct to ground. Contacts 109 and 110 are opened and closed by the operation of a relay Z in a circuit w ich may be traced round, wire 99, ring 101, contact 102, wire 100, rela Z wire 98, relay Z to grounded battery The circuit just traced is normall open at contact 102, but is adapted to he closed by armature spring 101, of a relay Z when this relay Z is energized. This relay Z is normally bridged across-the trunk or extension 13*-14 by the armature springs 104 and 105 of relays Z and Z which normally engage back cons tacts 130 and 131 connected to wlres 103 and 103 which are connected to the terminal wires of the relay Z When the called subscriber closes his circuit by removing his receiver from the hook and thus cuts battery back to line 15-16, the relay Z will be energized by this battery current flowing over wires 15-16 through contact wa -m wipers 42 -0 trunk extensions 13 -14, wires 123-121, springs 104-105, contacts 130-131, wires 103 -103 and relay Z causing its armature spring to close against contact 102, which thus closes the circuit for and energizes relays Z and Z? over the circuit heretofore described. The energizing of relay Z opens the circuit of relays Z and Z at contacts 92, 93 and 94 and the en ergizing of relay Z closes the circuit of relaysZ and Z These relays Z and Z" will thus be simultaneously ener ized but for the reason heretofore explained the normally closed circuit will be opened momentarily in advance of the closing of the normally open circuit, so that no release takes place at this time. Also relays Z and Z are similarly energized but Z opens its contact prior to the closing of contacts by Z so that the repeating relays Z and Z will be i cut off of lines 13 and 14 and the relays Z and Z immediately thereafter will be connected to lines 13 and 14, relay Z being in the branch 113 connected to grounded battery and relay Z being the in branch 114 which is connected direct to ground. As

the calling subscriber has his receiver oil the hook the subscribers loop including lines 13 and 14 is closed, and consequently relays Z and Z are simultaneously operated as heretofore described. This circuit may be traced as follows: grounded battery, contact 110, wire 113, rela Z, line wire 13 to calling subscribers station and back over line 14 relay Z wire 114, contact 109, to ground. The battery current thus flows through these two relays Z and Z feeding the calling subscribers end of the line with current for talking purposes whenever the relays Z and Z are simultaneously energized.

This brings us to the release circuit between the switches when the repeating trunk is employed, with the interposed condensers.

So long as the called subscriber has not answered and therefore has not energized the relay Z? and thus cut off the repeating relays Z and Z thesimultaneous grounding of the two sides of the line by the calling subscriber hanging up would simultaneously energize the relays Z andZ and would cause the armature springs 106 and 107 to close together in a manner similar to that heretofore described by the simultaneous energizing of relays D and E The circuit for energizing the rela s Z and Z could be traced as follows: from grounded battery, through wire 117, springs 107-106, wire 119, Z, contact m wiper 0 wire 52, to release relay J of the as heretofore described. in this release circuit in wire 119 a release relay Z which would be energized when the release for the first selector is closed. The energizing of this relay Z would simultaneously ground both sides of the extended line or trunk 13 and 14 through the armature springs 140-141 and wires 142-143, which connect to the trunk or extension lines l3 and 14 and this momentary grounding of both sides of the trunk line would operate the relays D and E nd cause the release of the second selector and connector switches in the manner heretofore described. In case the connection has been completed by the called subscriber answering and the repeating relays Z and Z have been cut out of circuit with the line wires 13 and 14 the. release would be effected through the relays Z and Z and their armature springs 115 and 116. When these relays Z and Z were simultaneously energlzed, armature spring 116 was opened and at the same time armature spring 115 was closed, both of these contacts being included 1n a branch of the release circuit extending from line 117, contact 116, wire 120, contact 115, wire 122 to release circuit is branched between wires 117 and 119, one branch includes the circuit closers 106 and 107 operated by relays Z and Z and the other branch includes the circuit closers 115 and 116 operated by relays Z and Z".

As before explained when the relays Z and Z are simultaneously energized and deenergized either one or the other of their circuit closers will be open and the other one of said circuit closers be closed. Inasmuch as one of the relays Z or Z is connected from one side of the line direct to ground wire 119, in other words the v the branch 113 which inclu es the battery. The contact for the armature spring 116 1s a back contact and closes when the relay Z is deenergized while the contact for armature spring 115 is-a frontcontact and closes when the rela CZ- is energized. .The result therefore of simultaneously grounding both sides of the wire is to close the branch 122 of the release circuit at contacts 115 and 116 and thus operate the release relay of the first selector switch or any switch which may be back of the contact m over the line 119 which as before described includes the release relay Z of the extension or trunk 13 and 14, and which. being energized would momentarily ground both sides of the trunk 13 and 14vand thus release the second selector and connector switches as before described. Consequently the momentary grounding of both sides of the line by the calling subscriber when he hangs up his receiver will release all the switches whether the called subscriber has answered or-not.

Having thus described our invention, we

claim 1. Ina telephone exchange s stem, a me 7 tallic trunk circuit having con ensers interposed in its two sides, a battery and controlling relays connected to the trunk at one side of the condensers and branches controlled by the relays leading to the other side thereof, the two conductors of the trunk circuit being transposed between the condensers and the point of con nectlon'to the y branches. c

. 2. In a telephone'exchange sy'st( am,--two metallic circuits, condensers interposed in the sides of one of said circuits,'-means for, repeating impulses from one metallic circult to-the other by causin the impulses transmitted over oneside 0 one circuit ;to' -.be repeated over-the other side ofthe other circuit, and branch conductors for said impulses connected to the sides of the second-}. mentioned metallic-circuit, said sides being transposed between thepoints of connection thereof with said branch conductors and said condensers. I

.3. In a telephone exchange system, two

metallic circuits, condensers interposed inthe sides of one of said circuits, means for repeating impulses from one metallic circult to the other by causin the impulses transmitted over one side 0 one circuit to be re eated over the other side ofthe other circuit, branch conductors for said impulses connected to the sides of the second-mentioned metallic circuit, said sides being transposed between the points of connection thereof with said branch conductors and said condensers, a trunk release circuit, and means associated with said repeating means for controlling said release clrcuit.

In testimony whereof, We.have hereunto set our hands this 6thday of Sept, 1909, and 31st day of August, 1909, respectively.

J AOOB W. LATT'IG.

CHARLES L. GOODRUM.

CHARLES CoMLY, WM. A. 'HA'rroN.

Witnesses to signature of Charles L.

Goodrum: v

EFFA M. SMITH, CHAS. 1. WELCH.

Witnesses to signature of Jacob W. Latl 

